add benchmark and incomplete implementation for event based tracing

Author: rochdev

benchmark/sirun/plugin-koa/README.md

@@ -0,0 +1,3 @@
+This creates 100,000 HTTP requests to a Koa server.
+
+The variants are with the tracer, without it, and with a new internal tracer.

benchmark/sirun/plugin-koa/agent.js

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+'use strict'
+
+const express = require('express')
+const bodyParser = require('body-parser')
+
+const app = express()
+
+let requests = 0
+let bytes = 0
+
+app.use(bodyParser.raw({ limit: '50mb', type: () => true }))
+app.use('*', (req, res) => {
+  requests++
+  bytes += req.body.length
+
+  console.log(`Requests: ${requests}`) // eslint-disable-line no-console
+  console.log(`Bytes: ${bytes}`) // eslint-disable-line no-console
+
+  res.status(200).send()
+})
+
+app.listen(8126)

benchmark/sirun/plugin-koa/internal-tracer/client.js

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+'use strict'
+
+const http = require('http')
+const https = require('https')
+const { dockerId, storage } = require('../../../../packages/datadog-core')
+const tracerVersion = require('../../../../package.json').version
+
+const httpAgent = new http.Agent({ keepAlive: true, maxSockets: 1 })
+const httpsAgent = new https.Agent({ keepAlive: true, maxSockets: 1 })
+
+const DD_TRACE_AGENT_URL = process.env.DD_TRACE_AGENT_URL || process.env.DD_TRACE_URL
+
+class Client {
+  request (options, done) {
+    if (options.count === 0) return
+
+    const url = new URL(DD_TRACE_AGENT_URL || 'http://127.0.0.1:8126')
+    const isSecure = url.protocol === 'https:'
+    const isUnix = url.protocol === 'unix:'
+    const client = isSecure ? https : http
+    const agent = isSecure ? httpsAgent : httpAgent
+    const data = options.data
+    const timeout = 2000
+    const httpOptions = {
+      agent,
+      protocol: url.protocol,
+      hostname: url.hostname,
+      port: url.port,
+      socketPath: isUnix && url.pathname,
+      path: options.path,
+      method: 'PUT',
+      headers: {
+        'Content-Length': String(data.length),
+        'Content-Type': 'application/msgpack',
+        'Datadog-Container-ID': dockerId || '',
+        'Datadog-Meta-Lang': 'nodejs',
+        'Datadog-Meta-Lang-Version': process.version,
+        'Datadog-Meta-Lang-Interpreter': process.jsEngine || 'v8',
+        'Datadog-Meta-Tracer-Version': tracerVersion,
+        'X-Datadog-Trace-Count': String(options.count)
+      },
+      timeout
+    }
+
+    const onResponse = res => {
+      let data = ''
+
+      res.setTimeout(timeout)
+      res.on('data', chunk => {
+        data += chunk
+      })
+      res.on('end', () => {
+        if (res.statusCode >= 200 && res.statusCode <= 299) {
+          try {
+            const response = data
+            done(null, response)
+          } catch (e) {
+            done(e)
+          }
+        } else {
+          const statusCode = res.statusCode
+          const statusText = http.STATUS_CODES[res.statusCode]
+          const error = new Error(`Error from the agent: ${statusCode} ${statusText}`)
+
+          error.status = statusCode
+
+          done(error, null)
+        }
+      })
+    }
+
+    const makeRequest = onError => {
+      const store = storage.getStore()
+
+      storage.enterWith({ noop: true })
+
+      const req = client.request(httpOptions, onResponse)
+
+      req.on('error', onError)
+
+      req.setTimeout(timeout, req.abort)
+      req.write(data)
+      req.end()
+
+      storage.enterWith(store)
+    }
+
+    makeRequest(() => makeRequest(done)) // retry once on error
+  }
+}
+
+module.exports = { Client }